Particularly in the case of vehicles with start/stop technology, i.e. when the engine is frequently switched off and on again during normal driving operation, comfortable running down of the internal combustion engine and rapid restarting of the internal combustion engine is of great importance.
JP-2008298031 A describes a method in which the throttle valve of the internal combustion engine is closed during rundown in order to suppress vibration. By means of this measure, the air charge in the cylinders in the internal combustion engine is reduced, thus reducing the roughness of rundown since compression and decompression are minimized.
To restart the internal combustion engine, however, as much air as possible is required in the cylinders in which ignition takes place for the restart. There is therefore a conflict of aims between rapid engine starting (which requires a large amount of air in the cylinder) and comfortable, i.e. low-vibration, engine rundown (which requires a small amount air in the cylinder).
Methods for restarting the internal combustion engine in which the internal combustion engine is allowed to come to a halt before it is restarted are common knowledge. Particularly in “change-of-mind situations”, in which there is a start request while the internal combustion engine is still running down, this leads to delays between the start request and engine starting, which are perceptible and felt to be inconvenient.
Devices which modify the stroke profile particularly of the inlet valves of the internal combustion engine and thus adjust the air charge in the cylinders are common knowledge in the prior art. In particular, the fact that the stroke profile of the inlet valves can be configured as desired within wide limits by means of electrohydraulic actuators is known. Internal combustion engines with such electrohydraulic valve adjustment do not require a throttle valve. It is likewise known that the stroke profile, particularly of the inlet valves, can be varied by adjusting the camshaft. Devices of this kind and the throttle valve, with which the air charge in the cylinders can be modified, are also referred to below as air metering devices.